[SOLVED] Debugging systemctl "inactive (dead)"

Debugging systemctl "inactive (dead)"

I wanted to determine why systemd-timesyncd refused to start at bootup without logging anything or offering useful information in systemctl status.

# systemctl status systemd-timesyncd
* systemd-timesyncd.service - Network Time Synchronization
   Loaded: loaded (/lib/systemd/system/systemd-timesyncd.service; enabled; vendor preset: enabled)
   Active: inactive (dead)
     Docs: man:systemd-timesyncd.service(8)

What steps can be done to determine what the issue is in the general case?

Solution

After doing a lot of reading of the excellent man files and bisecting a duplicated version of the service (which always "mysteriously worked", non-mysteriously in retrospect).

I discovered there was an unmentioned Conficts=... systemd-timesyncd.service with vboxadd-service.service.

There was no hint in the logs (presumably systemd.log_level=debug would have helped here based upon https://github.com/systemd/systemd/issues/7104).

I was able to notice the conflict only by examining the output of

systemd-analyze dot systemd-timesyncd.service

which provided the hint of a conflict.

In general you can list all conflicting services using

# systemd-analyze dot systemd-timesyncd.service 2>/dev/null | grep red
    "systemd-timesyncd.service"->"shutdown.target" [color="red"];
    "vboxadd-service.service"->"systemd-timesyncd.service" [color="red"];

or a command like

# systemctl show '*' -p Id,Conflicts | grep -B1 '^Conflicts=.*systemd-timesyncd' | sed -n 's/^Id=//p'
vboxadd-service.service